Taking a random guess, I think it’s because the location of the AppleTV doesn’t help identify the location of the actual screen. There would need to be some awkward configuration step (redone every time the AppleTV or screen moves) that Apple just wouldn’t ask its customers to do.
You don't really need an awkward configuration step, though, because you can rely on the fact that users are usually looking at the screen. Just take the median orientation of the earbuds over time, and you're configured.
You can also rely on the fact that the user is almost certainly looking directly at the screen every time they navigate the UX with the remote.
When I use spatial audio on my 2019 ipad it works like that. If I move my head to the side for a while, it "reorients", and now the audio comes from a point in the air next to the ipad.
Oh, I love this line of thought! However, I'd switch it to be multi-modal, i.e. not just "median orientation of earbuds over time", but also ___.
Specifically, one more example, people need to use their AirPods with a TV because the rest of the household needs quiet. However, there are typically speakers already set up "correctly" oriented (especially with surround sound).
The AppleTV and AirPods could automatically communicate through the individual speakers (at frequencies we can't hear), to correlate the user's location/orientation in relation with the "optimal sitting spot, based on audio".
In my testing with spatial audio, the effect doesn't seem to change with distance, so I think direction is all it relies on.
I could be wrong though, it might be doing something subtle. But even if it were, it would still be fine to fall back to a default distance of 2m or something.
I wonder if a U1 UWB chip be precise enough to detect if if the ATV has moved. Using 1 HomePod mini as a reference point, and more precision with more HomePods.
The location of the screen could be learned with some "Apple Magic," i.e. an AR setup process using an iPhone
All they need is a "look at your TV" step. User looks at TV, ATV saves AirPod gyro orientation and you are done. The iPhone/iPad need their orientation because the screen can move at any point...TV's usually don't.
